A Simple Synthesis of Stable Phosphoranes Derived from Imidazole Derivatives

Stable crystalline phosphorus ylides were obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine and dialkyl acetylenedicarboxylates, in the presence of strong NH-acids, such as imidazole, 2-methylimidazole, 4-methylimidazole, 2-ethylimidazole, benzimidazole, and 5,6-dimethylbezimidazole. These stable ylides exist in solution as a mixture of two geometrical isomers as a result of restricted rotation around the carbon–carbon partial double bond resulting from the conjugation of the ylide moiety with the adjacent carbonyl group.     

A Simple Synthesis of Stable Phosphorus Ylides from Indole and Some of Its Derivatives

Stable crystalline phosphorus ylides were obtained in excellent yields from the 1:1:1 addition reaction between triphenylphosphine and dialkyl acetylenedicarboxylates in the presence of strong NH acids, such as indole and 2-methyl indole, 3-methyl indole, and 5-boromo indole. These stable ylides exist in a solution as a mixture of two geometrical isomers as a result of the restricted rotation around the carbon–carbon partial double bond resulting from the conjugation of the ylide moiety with the adjacent carbonyl group.     

A Simple Synthesis of Stable Phosphorus Ylides Derived from 2-Benzoxazolinone and 2-Mercaptobenzoxazole

The reaction of triphenylphosphine with dialkyl acetylenedicarboxylates in the presence of a strong SH-acid or NH-acid, such as 2-mercaptobenzoxazole and 2-benzoxazolinone, has been studied. In some cases, stable phosphorus ylides are obtained in excellent yields. The ylide moiety of these compounds is strongly conjugated with the adjacent carbonyl group, and the rotation about the partial double bond in (E) and (Z) geometrical isomers is slow on the NMR time scale at an ambient temperature. Thus, these exist as a mixture of geometrical isomers.     

An efficient one-pot multi-component synthesis of 3,4,5-substituted furan-2(5H)-ones catalyzed by tetra-n-butylammonium bisulfate

A facile one-pot synthesis of 3,4,5-substituted furan-2(5H)-one derivatives from a three-component reaction of aniline derivatives, dialkylacetylenedicarboxylates and aromatic aldehydes under mild conditions using tetra-n-butylammonium bisulfate as a catalyst has been developed.     

Intramolecular hydrogen bonding in chemoselective synthesized 2-substituted pyrrole stable phosphorus ylide: GIAO, AIM, and NBO approaches

The chemoselectivity of geometrically ylide compounds is often hard to assign from experimental techniques, particular system with intramolecular hydrogen bonding (IHB) are even more challenging. Herein, theoretical calculations were performed to investigate whether theoretical results would provide consistent evidence for the existence of IHB to confirm experimental data and to evaluate strength of the N–H···O IHB from geometrical synthesized 2-substituted pyrrole stable phosphorus ylide (dimethyl 2-(1H-pyrrol-2-yl)-3-(triphenylphosphoranylidene) butanedioate in a single chemoselective compound. Topological parameters at the bond critical points (BCP) of intramolecular hydrogen bonds from Bader’s atoms in molecules (AIM) theory and Winhold’s natural bond orbital (NBO) calculations were analyzed at the B3LYP/6-311++g** level in details. A series of gage-including atomic orbital chemical shift (GIAO c.s.) calculations at the HF and DFT levels of theory were carried out to assign the ¹H NMR chemical shifts. The best prediction of the experimental ¹H NMR values was obtained at the mPW1PW91 levels using the 6-31G** basis set. Theoretical results, in agreement with the experimental data, were confirmed the N–H···O IHB was caused the deshielding of the proton to lower field. The barriers in double bond and single bond rotation were theoretically estimated in detailed and the AIM and NPA approaches were confirmed the loss of charge of the hydrogen atom involving in intramolecular N–H···O hydrogen bonding. The geometrical and topological parameters from AIM and NBO analyses were indicated the medium N–H···O IHB.     

Fe(NO3)3·9H2O as Efficient Catalyst for One‐pot Synthesis of Highly Functionalized Piperidines

Fe(NO₃)₃·9H₂O is used as an efficient and effective catalyst for the one‐pot three‐component synthesis of highly functionalized piperidines from aromatic aldehydes, anilines and b–ketoesters in ethanol at ambient temperature. This procedure includes some important aspects like the easy work‐up, no need to column chromatography, simple and readily available precursors, and good to high yields.     

A simple and effcient approach to one-pot synthesis of mono- and bis-N-aryl-3-aminodihydropyrrol-2-one-4-carboxylates catalyzed by InCl3简

An efficient and straightforward procedure has been developed for the synthesis of highly substituted mono- and bis-N-aryl-3-aminodihydropyrrol-2-one-4-carboxylates via a one-pot, four-component domino reaction of amines, dialkyl acetylenedicarboxylates and formaldehyde in the presence of InCl3 （20 mol%） in MeOH at ambient temperature. The salient advantages of this method are mild reaction conditions, environmentally benign, high to excellent yields, shorter reaction times, easy operation and no column chromatographic separation.     

Diastereoselective Synthesis of Novel Benzofuran Derivatives by Euparin as a Natural Compound with DMAD in the Presence of Trialkyl Phosphite

An efficient, simple, and diastereoselective synthesis of novel benzofuran phosphonato ester derivatives has been achieved via a one‐pot three‐component reaction of euparin as a natural product, trialkyl phosphate, and dimethyl acetylenedicarboxylate (DMAD) in diethyl ether without using any catalyst at room temperature. NMR spectroscopic data and X‐ray crystallography analysis are in agreement with the anti arrangement for the two vicinal protons in the structures, and only one diastereoisomer (2S,3R) or (2R,3S) was obtained for the products. The advantage of our research is that this is the first report for the diastereoselective synthesis of phosphonato ester derivatives from a green natural product. This one‐pot reaction occurs in high yields with easy work‐up under mild conditions. All pure products were obtained by recrystallization from ethanol, and there was no need for column chromatography.     

Al(H_2PO_4)_3 as an Efficient and Reusable Catalyst for One-pot Three-component Synthesis of α-Amino Phosphonates under Solvent-free Conditions

Synthesis of α‐amino phosphonates is described under solvent‐free conditions at 100°C from reaction between aldehydes and amines in the presence of trialkyl phosphites using Al(H₂PO₄)₃ as an efficient and reusable heterogeneous catalyst. The advantages of this procedure are short reaction time, flexibility and having high to excellent yields.     

An efficient synthesis of 2,2′-arylmethylene bis-(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) and 1,8-dioxooctahydroxanthenes using ZnO and ZnO-acetyl chloride

<正>2,2'-Arylmethylene bis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) 4l-s produced from reaction between dimedone with various aldehydes in acetonitrile using ZnO as a catalyst;whereas in the presence of ZnO-acetyl chloride catalysts the reaction is limited to give only 1,8-dioxo-octahydroxanthenes 3a-k in very good yields.